1. Field of the Invention
The present invention relates generally to water tank heating devices. More specifically, the invention relates to a portable water tank heating system which utilizes a continuous tubular loop that is filled with a fluid which is circulated through the tubular loop by convection to prevent the water in a drinking tank from freezing.
2. Description of the Prior Art
In climates where the weather becomes very cold for extended periods of time, the livestock industry encounters many problems and challenges when water in the livestock watering tanks becomes frozen, thereby preventing the livestock from having free access to water. One of the challenges is to provide a water tank heating device with an appropriately protective housing which protects the heater and components of the system even under severe weather conditions. In remote areas, electric power is often not available for powering a water tank heating device. Further, the use of electric power may be impractical or unsafe. Further, the use of solar power in geothermal units is very expensive, and such units are difficult to construct. Many different devices have been developed to deal with the problems and challenges, as exemplified by the following prior art:
U.S. Pat. No. 237,689, issued on Feb. 15, 1881, to Odile Martin, discloses an incubator that uses a gas burner to heat a fluid that circulates by convection and exchanges heat with the incubator-warming chamber to keep the incubator warm. The closed loop fluid heating system disclosed in the incubator of Martin is constructed as an internal part of the device rather than as a portable, external unit like the present invention.
U.S. Pat. No. 1,524,804, issued on May 27, 1924, to Thomas W. Dougherty, discloses a hog watering trough that heats the water circulating in a loop which is open to the trough to keep the water in the trough at a proper drinking temperature. The heating system of the watering trough of Dougherty uses an open loop and is internal to the hog waterer unlike the present invention.
U.S. Pat. No. 2,126,657, issued on Oct. 9, 1936, to Leslie T. Petersen, discloses a livestock watering tank which is heated by a gas burner and in which the water is circulating by convection. The watering tank of Petersen has neither the external heating system or the closed-loop fluid heat exchange of the present invention.
U.S. Pat. No. 2,612,138, issued on Jul. 5, 1950, to Reinhard C. Lindemann, discloses an animal watering fountain which prevents the water in a livestock watering trough from freezing. The fountain of Lindemann has neither the external heating system nor the closed-loop heating of the present invention.
U.S. Pat. No. 3,306,263 issued on Apr. 22, 1965, to Glen J. Johnson, discloses a livestock watering system which prevents the water in the trough from freezing by circulating the water in the tank with the water from a tank located underground below the frost line. The watering system of Johnson has neither the gas-powered heating system nor the closed-loop heating of the present invention.
U.S. Pat. No. 3,618,569, issued on Nov. 9, 1971, to Stephen C. Baer, discloses a device for preventing the water in a livestock watering hole from freezing which consists of a continuous loop tubing filled with a liquid which will circulate through the loop by convection and exchange heat absorbed from the bottom of the watering hole with the water on the surface of the watering hole to prevent it from freezing. The Baer device utilizes a closed loop and is portable. The device is completely submerged, however, making it difficult to use, and it relies on natural differences in temperature to cause convection rather than a gas burner which allows more heat to be exchanged into the water.
U.S. Pat. No. 4,280,556, issued on Jul. 28, 1981, to George H. Cooper, discloses a heat exchange tank assembly for a hot water heating system which utilizes a heated liquid circulating through a closed loop by convection to warm the water in a hot water tank. The closed loop heating system of the hot water heating system of Cooper relies on solar radiation rather than gas heat which does not have the limitations of solar energy.
U.S. Pat. No. 4,320,720, issued Mar. 23, 1982, to Clifford P. Streed, discloses a livestock watering system which uses geothermal energy to heat a fluid in a closed loop. The fluid is evaporated by the geothermal heat and rises through the hot half of the loop and condenses next to the waterer to transfer heat to the waterer and keep the water heated. The waterer of Streed does not disclose the external heating system according to the present invention.
U.S. Pat. No. 5,138,980, issued on Aug. 18, 1992, to Frederick D. Ewing, discloses an animal liquid feeder system which uses an electrically-operated fluid heating and cooling system to circulate a fluid in a closed loop to regulate the temperature of the liquid animal feed in the system. The closed loop temperature regulating system of the Ewing liquid feeder is electrically operated rather than gas-operated which limits the locations in which it can be used.
French Patent Document Number 2,258,124, dated Aug. 18, 1975, by Philippe Pierre Marie et al., discloses an electrically-heated livestock watering tank. Marie does not show the closed loop liquid heating system nor the gas burner of the present invention.
French Patent Document Number 2,469,116, dated May 5, 1981, by Roger Naulet, discloses a float device for preventing freezing of a livestock watering tank The device is electrically operated, unlike the present invention.
Soviet Patent Document Number 1,672,004, dated Oct. 3, 1985, by N. V. Bogomolou et al., discloses a device which uses an electrically heated fluid circulated in a closed loop which extends into a tank for heating the liquid therein. The reference does not have the gas power heating device of the present invention.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed.